Membranes have seen a growing role in mitigating the extensive energy used for gas separations. Further expanding their effectiveness in reducing the energy penalty requires a fast separation process via a facile technique readily integrated with industrial membrane formation platforms, which has remained a challenge. Here, an ultrapermeable polyimide/metal-organic framework (MOF) hybrid membrane is reported, enabling ultrafast gas separations for multiple applications (e.g., CO 2 capture and hydrogen regeneration) while offering synthetic enhanced compatibility with the current membrane manufacturing processes. The membranes demonstrate a CO 2 and H 2 permeability of 2494 and 2932 Barrers, respectively, with a CO 2 /CH 4 , H 2 /CH 4 , and H 2 /N 2 selectivity of 29.3, 34.4, and 23.8, respectively, considerably surpassing the current Robeson permeability-selectivity upper bounds. At a MOF loading of 55 wt%, the membranes display a record-high 16-fold enhancement of H 2 permeability comparing with the neat polymer. With mild membrane processing conditions (e.g., a heating temperature less than 80 °C) and a performance continuously exceeding Robeson upper bounds for over 5300 h, the membranes exhibit enhanced compatibility with stateof-the-art membrane manufacturing processes. This performance results from intimate interactions between the polymer and MOFs via extensive, direct hydrogen bonding. This design approach offers a new route to ultraproductive membrane materials for energy-efficient gas separations.

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Polymers of Intrinsic Microporosity (PIMs) are broadly recognized as a potential next generation membrane material for gas separations due to their ultra-permeable characteristics. This mini review aims to provide an overview of these materials and capture its very essence, from chemistry to applications. PIMs-based gas separation membranes are divided into three main categories, i.e., neat PIMs, polymer blend PIMs, and mixed matrix PIMs membranes. This review covers a wide spectrum of PIMs with their gas diffusion mechanisms and separation performance, all of which are examined in detail. Core challenges and opportunities of PIMs membrane technology are reviewed, and this article concludes with future perspectives on PIMs. This mini review establishes a comprehensive understanding of the key technological competence and barriers of PIMs for next-generation gas separations membranes. S ignificant advances in the science and engineering of membrane materials and separation processes have been witnessed in recent decades. Membranes have demonstrated the capability of reducing the enormous amount of energy consumption for gas separations, compared to conventional thermally driven separation processes, like cryogenic distillation [1]. Indeed, membrane separation process is cost-effective and environmentally friendly with small physical footprints. Interests of membrane technology have been growing increasingly in past decades. Key areas that membranes are at play include CO 2 capture, nitrogen generation, hydrogen/helium recovery, natural gas sequestration and biogas purification [2]. Regarded as a new family of membrane materials, Polymers of Intrinsic microporosity (PIMs) have exhibited extremely high gas separation productivity and drawn extensive attention world-widely. The intrinsic microporosity leverages PIMs membranes to far exceed the Robeson upper bound limit of polymeric membranes, which opens an entirely new avenue for gas separations [3]. This review addresses the key developments and advances of PIMs as a super-permeable membrane material for gas separations. Specifically, this paper presents a comprehensive overview of three imperative types of PIMs membranes: those made from, respectively, neat PIMs, polymer blend PIMs, and mixed matrix PIMs.

A previously reported polyimide, 6FDA/DETDA:DABA(3:2), was pyrolyzed under different protocols to produce carbon molecular sieve (CMS) dense film membranes for separation of important gas pairs, including pure gases CO 2 /CH 4 , O 2 /N 2 and mixture gases 50% CO 2 /50% CH 4 and 50% C 3 H 6 /50% C 3 H 8. This study investigated the effects of pyrolysis temperature, O 2 doping, and precrosslinking on the separation performance of 6FDA/DETDA:DABA(3:2) CMS membranes. Comparing to the precursor membranes, separation performance of all 6FDA/DETDA:DABA(3:2) CMS membranes improves significantly with both higher permeability and selectivity. The CMS film pyrolyzed with a novel method, i.e., 800 o C with precrosslinking, shows very attractive separation performance with CO 2 and O 2 permeability of 4678 Barrer and 683 Barrer, CO 2 /CH 4 , O 2 /N 2 selectivity of 71.5 and 8.0. Sorption measurements provide insight into the pore size distributions among these CMS membranes. The effects of these three parameters during pyrolysis on the CMS membranes gas separation performance are

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Forward osmosis (FO) has emerged as a new technology for desalination and exhibits potentials for applications where reverse osmosis is incapable or uneconomical for treating streams with high salinity or fouling propensity. However, most of current draw agents in FO are salts and difficult to be recycled cost- and energy-effectively. In this work, we demonstrate a new and facile approach to efficiently recover water from the FO process with enhanced water purity by using a binary ion liquid/hydrogel system. The hybrid ion liquid/hydrogel draw solution system demonstrated in this work synergistically leverages the thermoresponsive properties of both the ionic liquid (IL) and hydrogel to improve the overall FO performance. Our findings corroborate that the hydrogel mitigates the water flux decline of the IL as the draw agent and provide a ready route to contiguously and effectively regenerate water from the FO process. Such a route allows for an efficient recovery of water from the draw solute/water mixture with enhanced water purity, compared with conventional thermal treating of lower critical solution temperature IL draw solute/water. Furthermore, hydrogels can be used in a continuous and readily recyclable process to recover water without heating the entire draw solute/water mixture. Our design principles open the door to use low-grade/waste heat or solar energy to regenerate draw agents and potentially reduce energy in the FO process considerably.

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